import numpy as np
import cv2

if __name__ == '__main__':
    a = np.zeros((3, 3))
    # print(a)
    # cv2.imshow('a', a)
    cv2.namedWindow('img1', cv2.WINDOW_NORMAL)
    cv2.resizeWindow('img1', 500, 500)
    cv2.imshow('img1', a)
    cv2.waitKey(0)
    cv2.destroyAllWindows()
    a[1,1] = 255
    # print(a)
    cv2.imshow('img2', a)
    cv2.waitKey(0)
    cv2.destroyAllWindows()